G73: Providing a long description in another location with a link to it that
is immediately adjacent to the non-text content

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.0 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.0.

Description

The objective of this technique is to provide a way to link to remote long
descriptions in technologies that do not have a long description feature
built directly into them (e.g., longdesc) or where the feature is known to
not be supported.

With this technique, the long description is provided in another location
than the non-text content. This could be at another location within the same
URI or at another URI. A link to that long description is provided that is
immediately adjacent to the non-text content. The link can be immediately
before or after the non-text content. If the description is located along
with other text then put "End of description" at the end so that they know
when to stop reading and return to the main content. If a "Back" button will
not take the person back to the point from which they jumped, then a link
back to the non-text content location is provided.

This technique was commonly used in HTML before 'longdesc' was added to the
specification. In HTML it was called a D-Link because it was usually
implemented by putting a D next to images and using the D as a link to the
long description. This technique is not technology specific and can be used
in any technology that supports links.

Examples

Example 1: Bar chart

There is a bar chart on a Web page showing the sales for the top
three salespeople.

The short text alternative says "October sales chart for top three
salespeople."

Immediately after the non-text content is a small image denoting a
long description. The alternate text for the image is "Long
description of chart". The image links to the bottom of the page
where there is a section titled "Description of charts on this
page". The link points to this specific description: "Sales for
October show Mary leading with 400 units. Mike follows closely with
389. Chris rounds out our top 3 with sales of 350. [end of
description]"

There is a bar chart on a Web page showing the sales for the top
three salespeople.

The short text alternative says "October sales chart for top three
salespeople."

Immediately after the non-text content is a small image denoting the
long description. The alternate text for the image is "Long
description of chart". The image links to another page titled
"Description of charts in October Sales Report". The description
link points to this specific description: "Sales for October show
Mary leading with 400 units. Mike follows closely with 389. Chris
rounds out our top 3 with sales of 350. End of description.
<link>Back to Sales Chart</link>"

Example 3: Caption used as link

There is a chart. The figure caption immediately below the chart
serves as a link to the long description. The Title attribute of the
link makes it clear that this is a link to a long description.

Example 4: Transcript of an audio-only file

There is a recording of a speech by Martin Luther King. Links to the
audio file and the transcript appear side by side.

Related Techniques

Tests

Procedure

check for the presence of a link immediately before or after the
non-text content

check that the link is a valid link that points directly to the
long description of this particular non-text content.

check that the long description conveys the same information as
the non-text content

check for the availability of a link or back function to get the
user back to the original location of the non-text content

Expected Results

All 4 of the above are true

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.